This section provides background information related to the present disclosure which is not necessarily prior art.
Lighting modules are used in a variety of applications and for a variety of purposes, in most of which production of a highly uniform light source, e.g. uniform intensity throughout a particular transmittance area, is generally desirable. However, due to the engineering limitations such as available lighting sources and packaging considerations of lighting modules, a common issue is lack of uniformity of the light emitted from the lighting module. For example, many lighting modules utilize a series of light sources spaced apart by various distances in order to approximate a uniform light source; however, as the individual light sources are spaced further apart from one another the uniformity of light decreases and light spots (or hot spots) characterized by higher luminous intensity result. Such light spots are typically undesirable. This issue and attempts to resolve it are described in U.S. Pat. No. 5,499,112 to Kawai et al., dated Mar. 12, 1996, which graphically illustrates the variation of luminous intensity in relation to the spacing of lighting sources as well as an attempt to reduce this phenomenon.
One such application wherein light spots are undesirable is that of fluorescence photography and, in particular, western blotting. Western blotting was introduced in 1979 and is now a routine technique for protein analysis. Utilizing this technique, the specificity of the antibody-antigen interaction enables a target protein to be identified within a more complex protein mixture. In particular, based on known characteristics of a biomolecule of interest, different enzymes or fluorescent dyes are used to label the biomolecule of interest. Once labeled various methods of observation are utilized. For example, in DNA fluorescence image observation, a 465 nm blue LED-based backlight is used to excite the labeled DNA sample to fluoresce and a CCD camera is used for observation or photography. However, variations in luminous intensity of the blue light, e.g. light spots, can interfere with observation or photography.
Attempts to resolve the issue of light spots in fluorescence photography include utilizing light diffusers for diffusing light spots into a more uniform light of a larger area. However, while the utilization of light diffusers alone may reduce the appearance and noticeability of light spots produced by direct-type backlight modules, e.g. a backlight module wherein light travels directly from a light source at the back of the module to the transmittance area, in highly light sensitive applications the appearance of light spots persists. Further attempts include dispersing light from a light source in edge-type backlight modules, for example, by utilizing an LED array to irradiate light diagonally to a light transmission zone for preventing formation of light spots.
The various attempts at improving the uniformity of the luminous intensity of a light emitted from a lighting module are workable in some applications. However, some of the attempts are limited in increasing uniformity due to requiring an increase in light sources to further increase uniformity of light. Moreover, even the strategic placement of light diffusers between the light sources and the light transmission zone does not completely alleviate the appearance of light spots. Other attempts are limited in increasing uniformity due to a concentration of light, e.g. formation of light spots, at the edges of the transmission zone near the sources of light.